The overall objective of this project is to examine the cancer mortality experience in the United States relative to cancer etiology. Special emphasis is placed upon the selection of areas in the U.S. for intensive study. Publications from this area of interest have facilitated the design of ongoing analytical investigations to test specific etiologic hypothesis. An update to our earlier work in this area has been completed in the form of a three volume publication containing cancer mortality rates and changes in rates for counties of the United States for 1950-1959, 1960-1969, and 1970-1979. Age-adjusted mortality rates are ranked nationally by percentiles for 1970-1979, and for percentage change in the rates from 1950-1959 to 1970-1979. These volumes should facilitate the identification of places where additional study should be considered.